Fuel injector

ABSTRACT

A fuel injector for injecting fuel into a cylinder of an internal combustion engine is disclosed, wherein fuel is received from a variable pressure fuel supply and is supplied to a chamber in the injector, the injector also having spray holes for discharging fuel from said chamber to the cylinder. A reciprocable plunger in the injector is utilized to decrease the volume of the chamber and thus increase the pressure of the fuel therein. A pressure actuated valve in the chamber serves to permit fuel injection through the spray holes only when the pressure in the chamber, due to movement of the plunger, reaches a predetermined value sufficient to open the valve. The injector also includes a connection between the chamber and a low pressure zone or drain during part of the cycle of movement of the plunger. This connection permits fuel to be sucked into the chamber during said part of the cycle from the drain rather than from the supply. Since the plunger does not suck fuel from the supply, the quantity of fuel entering the chambe from the supply will be a function of the pressure of the fuel delivered by the supply.

[ Jan. 1,1974

ABSTRACT A fuel injector for injecting fuel into a cylinder of an internal combustion engine is disclosed, wherein fuel is received from a variable pressure fuel supply and is supplied to a chamber in the injector, the injector also having spray holes for discharging fuel from said chamber to the cylinder. A reciprocable plunger in the injector is utilized to decrease the volume of the chamber and thus increase the pressure of the fuel FUEL INJECTOR Inventor: Julius P. Perr, Columbus, lnd.

Assignee: Cummins Engine Company,

Columbus, lnd.

Dec. 30, 1970 22 Claims, 46 Drawing Figures therein. A pressure actuated valve in the chamber serves to permit fuel injection through the spray holes only when the pressure in the chamber, due to movement of the plunger, reaches a predetermined value sufficient to open the valve. The injector also includes a connection between the chamber and a low pressure zone or drain during part of the cycle of movement of i the plunger. This connection permits fuel to be sucked into the chamber during said part of the cycle from the drain rather than from the supply. Since the plunger does not suck fuel from the supply, the quantity of fuel entering the chambe from the supply will be a function of the pressure of the fuel delivered by the supply.

United States Patent [191 Perr j [22] Filed:

PAIENTEBJAN 119 4 sum 3 0r 9 1 FUEL INJECTOR In one type of fuel injection nozzle used in fuel supply systems of compression ignition engines the spray holes for injecting fuel into a cylinder are normally closed by j a valve. Such an injector includes an injector body having the spray holes formed therein, and the valve which normallycloses the spray holes is movable to open the spray .holes in response to an increase in pressure within theinjector body. A pumping member, usually a cam operated plunger within the injector body, is operable during an injection stroke to increase the fuel pressure to the point where the valve opens and permits flow of the fuelout of the spray holes.

Further, Reiners US. Pat. No. 3,159,152 discloses a fuel supply systemwherein the quantity of fuel injected into each cylinder in each cycle of the engine is dependent upon the pressure of the fuel supplied to the injectors. This pressure may be controlled in various ways, as by the engine speed or by an operator and the pressure is variable down to a low pressure level which is necessary to provide the small fuel quantities required at idling speeds.

It hasnot heretofore been possible satisfactorily to use an injectorof. the character described above in a variable pressure fuel supply system because they cannot respond to low fuel pressure levels andbecause conventional injectors of this character create a suction action during the retraction stroke of the pumping member. Such a suction action would make such a conventional injector unresponsive to changes in the pressure of the fuel supplied to the injector, thus losing the advantages inherent in a variable pressure fuel system.

sucked into the :injector comes from the drain which feature enables the injector to be responsive to the pressure of the fuel from the supply. Further, the applicants injectorresponds to low fuel pressure levels and itincludes an advantageous method of terminating injection.

Other objects and advantages of the invention will become apparent from the following detailed description and accompanying drawings, wherein:

FIG. 1 is an enlarged longitudinal sectional view of a fuel injector embodying the features of the invention and showing the positions of the parts thereof during one portion of the operating cycle of the injector;

FIG. 2 is a fragmentary longitudinal sectional view taken substantially along the line 2-2 of FIG. 1;

FIG. 3 is a longitudinal sectional view of the lower portion of the injector. shown in FIG. 1 and showing certain parts of the injector inthe positions they occupy during another portion of the operating cycle of the injector;

FIG. 4 is a fragmentary longitudinal sectional view taken substantially along the line 4-4 of FIG. 3;

FIG. 5 is a longitudinal sectional view, similar to FIG. 3, but showing certainparts of the injector in the positions they occupy during still another portion of the operating cycle of the injector;

FIG. 6 is a transverse sectional view taken along the line 66 of FIG. 1;

FIG. 7 is an enlarged longitudinal sectional view of another fuel injector embodying the features of the invention and showing thepositions of the parts thereof during one. portion of the operating cycle of the injector;

FIG. 8 is a fragmentary, longitudinal sectional view taken along the line 8--8 of FIG. 7;

FIG. 9 is a longitudinal sectional view of the lower portion of the injector shown in FIG. 7 and showing certain parts of the injector in the positions they occupy during another portion of the operating cycle of the injector; I

FIG. 10 is a fragmentary longitudinal sectional view taken along the line l0-10 of FIG. 9;

FIG. 11 is a longitudinal sectional view, similar to FIG. 9, but showing certain parts of the injector in the positions they occupy during still another portion of the operating cycle of the injector;

FIG. 12 is a fragmentary longitudinal sectional view taken along the line l212 of FIG. 11;

FIG. 13 is a generally transverse sectional view taken substantially along the line l313 of FIG. 7;

FIG. 14 is an enlarged longitudinal sectional view of another fuel injector embodying the features of the invention and showing the positions of the parts thereof during one portion of the operating cycle of the injector; 1

FIG. 15 is a fragmentary longitudinal sectional view taken substantially along theline 15-45 of FIG. 14;

FIGS. 16 and 17. are longitudinal sectional views of the lower portion of the injectorshown in FIG. 14, and i show certain parts thereof in the positions they occupy during differentportions of the operating cycle of the injector;

FIG. 18 is a fragmentary longitudinal sectional view, taken along the line I8I8 of FIG. 17;

FIG. 19 is a generally transverse sectional view taken along the line 19-19 of FIG. 14;

. FIG. 20 is an enlarged longitudinal sectional view of another fuel injector embodying the features of the invention and showing the positions of the parts thereof during one portion of the operating cycle of the injector;

FIG. 21 is a fragmentary longitudinal sectional view, taken substantially along the line 21-21 of FIG. 20;

FIGS. 22 and 23 are fragmentary longitudinal sectional views of the lower portion of the injector shown in FIG. 20, and show certain parts thereof in the positions they occupy during different portions of the operating cycle of the injector;

FIG. 24 is a fragmentary longitudinal sectional view taken along the line 2424 of FIG. 22;

FIG. 25 is a generally transverse sectional view taken along the line 25-45 of FIG. 20.,

FIG. 26 is an enlarged longitudinal sectional view of another fuel injector embodying the features of the in- FIGS. 27 and 28 are fragmentary longitudinal sectional views of the lower portion of the injector shown in FIG. 26, and show certain parts thereof in the positions they occupy during different portions of the operating cycle of the injector;

FIG. 29 is a generally transverse sectional view taken substantially along the line 2929 of FIG. 28;

FIG. 30 is an enlarged longitudinal sectional view of another fuel injector embodying the features of the invention and showing the positions of the parts thereof during one portion of the operating cycle of the injector;

FIGS. 31 and 32 are fragmentary longitudinal sectional views of the lower portion of the injector shown in FIG. 30, with portions thereof broken away, and show certain parts thereof in the positions they occupy during different portions of the operating cycle of the injector;

FIG. 33 is a generally transverse sectional view taken substantially along the line 3333 of FIG. 30;

FIG. 34 is an enlarged, longitudinal sectional view of another fuel injector embodying the features of the invention and showing the positions of the parts thereof during one portion of the operating cycle of the injector;

FIGS. 35 and 36 are fragmentary longitudinal sectional views of the lower portion of the injector shown in FIG. 34, and show certain parts of the injector in the positions they occupy during different portions of the operating cycle of the injector;

FIG. 37 is an enlarged, longitudinal sectional view of another fuel injector embodying the features of the invention and showing the positions of the parts thereof during one portion of the operating cycle of the injector;

FIG. 38 is a fragmentary longitudinal sectional view taken substantially along the line 38-38 of FIG. 37;

FIG. 39 is a longitudinal sectional view of the central portion of the injector shown in FIG. 37, but showing one of the parts thereof in the position it occupies during a different portion of the operating cycle of the injector;

FIGS. 40 and 41 are fragmentary longitudinal sectional'views of the lower portion of the injector shown in FIG. 37, and show certain parts thereof in the positions they occupy during different portions of the operating cycle of the injector;

FIG. 42 is a generally transverse sectional view taken along the line 4242 of FIG. 37;

FIG. 43 is an enlarged, longitudinal sectional view of another fuel injector embodying the features of the injector and showing the positions of the parts thereof during one portion of the operating cycle of the injector;

FIGS. 44 and 45 are fragmentary longitudinal sectional views of the lower portion of the injector shown in FIG. 43 and show certain parts thereof in the positions they occupy during different portions of the operating cycle of the injector; and

FIG. 46 is a generally transverse sectional view taken along the line 46-46 of FIG. 45.

Briefly described, the present invention contemplates a novel fuel injector that is adapted for use in a fuel supply system for an internal combustion engine of the compression ignition type. A fuel supply system with which the present injector is adapted for use is disclosed and claimed in the Reiners US. Pat. No. 3,159,152 issued Dec. 1, 1964.

The fuel injector herein contemplated has an elongated body having variable volume chamber means therein having an opening adapted to communicate with the cylinder of the associated engine. A pressure actuated valve member is movably mounted in the injector body and is urged in a direction to close the opening in the variable volume chamber means by a spring, such spring preventing the valve member from moving to a position permitting fuel to flow through the opening in the variable volume chamber means until the pressure therein rises to a predetermined value.

The injector body further includes fluid displacement means which is reciprocably mounted therein and which in part defines the variable volume chamber means. A fuel supply passage is also provided in the injector body, such passage having one end connected to the variable volume chamber means and the other end adapted to be connected to a source of fuel under variable pressure so that varying quantities of fuel are supplied to the variable volume chamber means for controlling the power output of the engine.

In all but one of the embodiments of the injector, to be hereinafter described in detail, the fluid displacement means comprises a plunger reciprocably mounted in a bore in the injector body, and a piston movable in response to movement of the plunger. In these embodiments, the piston determines the volume of the variable volume chamber means, while in the one embodiment the plunger alone determines the volume of the variable volume chamber means. In all but two of the embodiments, the piston is mounted in the bore of the plunger, while in these two embodiments the piston is mounted in a separate bore in the injector body.

In all of the embodiments which utilize pistons to determine the volume of the variable volume chamber means, the size of the variable volume chamber means at the start of the injection phase of the injection cycle is determined by the position of the piston in its bore and such position is controlled by the pressure of the fuel supplied to the injector. However, since the maximum extent of movement of the piston in its bore is limited by a stop at one end of the piston bore, the volume of'the variable volume chamber means is also limited to a predetermined maximum. Such stop either comprises one end of the plunger, one end of the plunger bore, or one end of a separate bore in the injector body in which the piston is mounted. In the embodiment in which the plunger alone determines the volume of the variable volume chamber means, since the stroke of the plunger is controlled by a cam and thus does not change, the volume of the variable volume chamber means of this embodiment is likewise limited to a predetermined maximum. Consequently, in all embodiments, the maximum quantity of fuel that can be injected by the injector during any one cycle of operation is limited and cannot be increased even though the pressure of the fuel supplied to the injector is caused to exceed some predetermined maximum or the drain passage of the injector is restricted in an undesired manner.

In all of the embodiments, the variable volume chamber means of the injector is in two parts, namely, a fuel receiving chamber and a fuel injection chamber. The fuel receiving chamber is separated from the fuel injection chamber and is connected thereto by a connecting passage in the injector body.

In all of the embodiments of the invention, preventing means is provided for preventing gas or other foreign particles from flowing from the receiving chamber into the fuel supply passage toward the source. Such preventing means prevents possible contamination of the. fuel supply to other injectors if the valve member of an injector should stick in an open position.

In all of the embodiments of the invention, the injector body includes adrain passage which permits excess fuel to be freely expelled from the injector during the operating cycle thereof. In the embodiments which utilize apiston to determine the" variable volume chamber means, one end of the drain passage communicates with the opposite side of the piston from the side which defines the variable volume chamber means. The other end of the drain passage is adapted to be connected to an associateddrain. In the embodiment of the invention in which the plunger alone determines the variable volume chamber means, the one end of the drain pas- I sage communicates directly with the variable volume pressure in the variable volume chamber means shortly before the plungercompletes its fuel injection stroke. Such pressure relief passage means has one end con nected to the drain passage and the other end connected to the variable volume chamber means, the connection of the one end of the pressure relief means being cyclically established and interrupted by the plunger. In all but one of the embodiments, the pressure of the fuel in the variable volume'chamber means is vented to the drain passage of the injector while in the one embodiment, such pressure is vented to the fuel supply passage.

In one of the embodiments, an arrangement is. provided whereby the force exerted by the spring on the valve member tending to move the valve member to a closing position increases as the plunger moves in a direction to inject fuel. Such arrangement provides a sharp cutoff of fuel at the end of the fuel injection stroke of the plunger and reduces the possibility of secondary injection.

The Embodiment Shown in FIGS. 1-6

' In FIGS. 16, inclusive, a fuel injector embodying the features of thepresent invention is illustratedLThe in- 1 jector shownin the figures comprises an elongated in- I are arranged in end-to-end relation and are held in such relation by a tubular retainer 106. In the present instance, theupper end, indicated at 107,.of the retainer 106 is internally threaded, as at 110, to receive the threaded lower end, indicated at 1 1 l, of the body member 102. The lower end of the retainer 106 is provided with an internal flange 112 for engaging an annular, radially outwardlyextending flange .113 on the nozzle member 103. Thus, when the retainer 106 is threaded onto the lower end 111 of the body member 102 as shown in FIG. 1, the body member 102, nozzle member 103 and intermediate spacer members 104 and 105 are held in abutting, end-to-end relation.

The body member 102 has a central, axial bore 114 therethrough in which a plunger 116 is reciprocably mounted. The plunger 116 includes a control portion 117, and a sleeve portion 118 secured to the upper end of the control portion 117. A flange 122 is provided on the upper end of the sleeve portion 118 to provide an abutment for one end of a coil spring 123 disposed around the sleeve portion 118. The other or lower end of the coil spring 123 bears against the bottom 124 of a large counterbore 126 in the upper end of the body member 102. The spring 123 is normally under compression and tends to urge the plunger 116 upwardly.

pressure through a fuel supply passage 130-having one end connected to the variable volume chamber means and the other end thereof adapted to be connected to said source. Said other end of the fuel supply passage 130, in the present instance, includes a circumferential groove 131 in the outer surface of the body member 102, the groove 131 being adapted to register with an associated fuel supply bore or rail (not shown) in the cylinder head of the engine. A transverse bore 132 extends inwardly from the groove 131 and a plug 133 (FIG. 1) having a balancing orifice 134 therethrough is threaded into the outer end of the bore 132. The balancing orifice 134 restricts and meters the flow of fuel through the fuel supply passage 130 and a filtering screen assembly 136 may be mounted in the groove 131 around the plug 133 to prevent foreign particles from entering the fuel supply passage 130.

The inner end of the transverse bore 132 is intersected by the upper end of a longitudinal bore 137 in the injector body member 102, and the lower end of the longitudinal bore 137 is counterbored as at 138 to define an annular seat 139 for a check. ball 140 mounted in the counterbore 138. The check ball 140 comprises preventing means for preventing fuel from flowing out of a receiving chamber in the injector body 101, to be hereinafter described in detail, and in a reverse direction through the fuel supply passage 130 into the fuel supply rail in the engine cylinder head during the fuel injection phase of the injection cycle. The

lower end of the counterbore 138 communicates with a shallow, circular cavity or recess 141. in the upper end face of the spacer member 104. The lower end of the plunger bore 114 also communicates with the cavity 141.

The aforementioned variable volume chamber means is in two parts and comprises a receiving chamber 142 and a fuel injection chamber 143. The receiving cham- In order to provide a connection between the receiving chamber 142 and the fuel injection chamber 143, a connecting passage, indicated generally at 146, is provided. The passage 146, in the present instance, comprises at least one and preferably a pair of diametrically spaced, longitudinal bores 147 and 148 in the spacer member 104, the upper ends of the bores 147 and 148 extend from the cavity 141 and the lower ends of the bores 147 and 148 intersect an annular groove 150 in the lower end face of the spacer member 104. Another longitudinal bore 151 is provided in the lower spacer member 105, the bore 151 being located in the spacer member 105 so that the upper end thereof registers with the annular groove 150 when the parts of the injector of FIG. 1 are in assembled relation.

The lower end of the longitudinal bore 151 may be counterbored as at 152 to define an annular seat 153, and a check ball 154 may be mounted in the counterbore 152 for engaging the seat 154. If so provided, the check ball 154 comprises preventing means for preventing gas or pressure waves from passing upwardly in the bore 151 from the fuel injection chamber 143 toward the balancing orifice 134 and into the associated fuel supply bore or rail in the cylinder head of the engine in the event of failure or malfunction of the injector.

The counterbore 152 registers with an annular groove 155 in the upper end face of the nozzle member 103, and a slanting bore 156 in the nozzle member 103 interconnects the groove 155 with the fuel injection chamber 143. Thus, the connected longitudinal bores 147 and 151 in the spacer members 104 and 105, respectively, and the bore 156 in the nozzle member 103 comprise the connecting passage 146 which connects the receiving chamber 142 with the fuel injection chamber 143.

As heretofore mentioned, the variable volume chamber means includes an opening adapted to communicate with the cylinder of the engine with which the injector of FIG. 1 is associated and through which fuel is injected into the cylinder. In the present instance, such opening comprises a plurality of minute, circumferentially spaced, generally radially extending holes 157 in the lower end of the nozzle member 103, the inner ends of the holes 157 being adapted to be placed in communication with the fuel injection chamber 143 during the fuel injection phase of the injection cycle.

For establishing communication between the fuel injection chamber 143 and the holes 157 so that fuel under pressure may flow therethrough and into the associated cylinder when the pressure of the fuel in the fuel injection chamber reaches a predetermined value, and for interrupting such communication, a valve member is provided. Such valve member is indicated generally at 158 and includes a valve body 159 shiftably mounted in an axial bore 160 in the nozzle member 103 in close-fitting relation therewith. The valve body 159 includes a reduced diameter portion 162 which extends downwardly from the lower end thereof and which defines a shoulder or fluid pressure reaction surface 163 on the valve body 159. The lower end of the reduced diameter portion 162 is tapered as at 164 for engagement with a complementally shaped seat 166 at the lower end of the fuel injection chamber 143. The inner ends of the holes 157 open into a depression below the seat 166 in the nozzle member 103. Thus, the fuel flow from the fuel injection chamber 143 to the holes 157 is prevented when the tapered lower end 164 of the valve body 159 engages its seat 166.

The lower end 164 of the valve member 158 is normally urged toward its seat 166 by a coil spring 172 mounted in a cavity 173 in the spacer member with the upper end of the spring 172 engaging the lower end face of the spacer member 104. The lower end of the spring 172 engages an abutment in the form of a circular plate 174 at the lower end of the cavity 173, the lower face of the plate 174 being seated on the upper end of an extension 177 on the upper end of the body portion 159 of the valve member 158. The spring 172 is precompressed and holds the lower end 164 of the valve member 158 on its seat 166 until a predetermined pressure is obtained in the fuel injection chamber 143 sufficient to overcome the force of the spring 172 and lift the valve member 158 off of its seat 166.

As heretofore mentioned, a piston in the form of the ball 144 is mounted in the plunger bore 114 between the lower end face 145 of the plunger and the cavity 141 in the upper end face of the spacer member 104. The ball 144 is loosely fitted in the plunger bore 114 and is movable in response to movement of the plunger. Since the ball 144 determines the volume of the receiving chamber 142 and is movable in response to movement of the plunger 116, the plunger and ball 144 comprise fluid displacement means for reducing the volume of the receiving chamber 142 and for increasing the pressure therein and in the fuel injection chamber 143.

In addition, since the volume of the receiving chamber 142 is determined by the ball 144 and since the volume of the receiving chamber 142 will be at a maximum when the ball 144 is engaged with the end face 145 of the plunger when the latter is at the end of its upward stroke, the end face 145 of the plunger comprises a stop limiting movement of the ball 144 in one direction and the volume of the receiving chamber 142 to a predetermined maximum. Consequently, the maximum quantity of fuel that can be injected into the associated cylinder is also limited.

In order to provide for variation of the volume of the receiving chamber 142, the space, indicated at 183, between the upper side of the ball 144 and the lower end face 145 of the plunger 116 is connected to a drain or other low pressure zone, such as a drain rail in the engine cylinder head. Connection of the space 183 to a drain permits fuel to be freely drawn into the space 183 from the drain and thus prevents any substantial vacuum from being created in the space 183, which would tend to cause the ball 144 to remain in contact with or closely follow the lower end face 145 of the plunger 116 during its upward stroke. Thus, the extent of upward movement of the ball 144 in the plunger bore 114 is determined substantially only by the pressure of the fuel in the fuel supply passage and this pressure is a direct function of the pressure of the fuel in the associated fuel supply rail in the engine cylinder head.

Connection of the space 183 above the ball 144 to the drain is provided by a drain passage having one end connected to the space 183 and its other end adapted to be connected to the drain. Such drain passage, in the present instance, comprises an axial bore or duct 184 in the lower end of the control portion 117 of the plunger 116, the lower end, indicated at 186, of the duct 184 opening in the end face of the plunger 187 in a reduced diameter portion 188 of the control portion 117 of the plunger, the reduced diameter portion 188 defining an annular space 189 in the plunger bore 114. The annular space 189 is in continuous registry with the inner end, indicated at 192, of a bore 193 slanting upwardly and outwardly in the injector body member 102 from theplunger bore 114. The outer or upper end of the bore 193 opensinto a circumferential groove 194 in the outer surface of the injector body member 102, the groove 194 being adapted to communicate with an associated drain bore or return rail in the cylinder head of the engine when the injector body 101 is seated in the cylinder head. Thus, the space 183 above the ball 144 is connected to the drain so long as the lower end 186 of the duct 184 is not closed by the ball 144. i

t lnjection of fuel into the engine cylinder occurs in a manner to be described hereafter in connection with the description of the operation of the injector.

The injector of FIG. 1 further includes pressure relief passage means for relieving the pressure in the receiving chamber 142 and fuel injection chamber 143 as the plunger 116 is approaching the end of its downward or fuel injection stroke. Such pressure relief passage means, in the present instance, comprises a pair of diametrically spaced, longitudinal bores 197 and 198 (FIGS. 2, 4 and 6) in the injector body member 102. The lower ends of the bores 197 and 198 communicate with the cavity l41 in the upper end face of the spacer member 104, and the upper ends of the bores 197 and 198 respectively intersect a pair of diametrically arranged transverse bores 201 and 202 in the body member 102. The outer ends of the transverse bores 201 and 202 are closed, as by plugs, and the inner ends thereof, indicated at 203 and 204, respectively, are restricted and open into the plunger bore 114. The restricted inner ends 203 and 204 of the bores 201 and 202 are located so asto communicate with the annular space 189 before the plunger 116 reaches the end of its downward or .fuel injection stroke. Thus, when the lower or control edge, indicated at 206,'of the reduced diameter portion 188 moves across the ends 203 and 204 of the transverse bores 201 and 202, pressure in the receiving and fuel injection chambers 142 and 143 is relieved and the fuel injection phaseof the injection cycle is terminated. However, since the inner ends 203 and 204 are restricted, the flow therethrough is small and the valve member 158 moves downwardly toward itsseat at a slower rate than if the ends 203 and 204 were unrestricted. Such downward movement of the valve member 158 causes fuel to be displaced from the fuel injection chamber 143 upwardly to the receiving chamber 142 and ultimately to the transverse bores 201 and. 202. The restricted inner ends 203jand 204 1 173 to an annular groove 208 in the outer periphery of the spacermember 105. The groove 208 opens into an annular clearance 209 between the spacer members 105 and 304 and the retainer 106. The upper end of the clearance 209 communicates with the lower end of a longitudinal bore 212 in the injector body member 302 and the upper end of the bore. 212 intersects the drain bore 193 to complete the vent connection to drain.

OPERATION OF THE EMBODIMENT SHOWN IN FIGS. 1+6

At the completion of an injection cycle of the injector shown in FIGS. 16, inclusive, and prior to the beginning of another cycle, the parts of the injector are in the positions shown in FIGS. 1 and 2. Thus, fuel under pressure maintains the ball piston 144 in the plunger bore 1 14 engaged with the lower end face 145 of the plunger 116 so that the ball closes the lower end 186 of the duct 184 in the control portion 117 of the plunger 116. The ball 144 is held against the lower end face 145 of the plunger by the differential pressure between the pressure in the receiving chamber142 and the pressure in the space 183 above the ball, the space 183 being connected to the drain.

As the injection cycle begins,.thej plunger 116 begins to move upwardly in its bore. If the pressure of the fuel in the associated fuel supply bore or rail is insufficient to fill the receiving chamber 142 :at a rate such as will maintain the ball 144 engaged with the lower end 186 of the duct 184 as the plunger 1 16 moves upwardly, the ball 144 will separate from the lower end 186 of the duct and the space 183 above the ball will increase. Such condition is shown in FIGS. 3 and 4.

During the upward stroke of the plunger 116., the lower or control edge 2060f the reduced diameter portion 188 moves across and closes. the inner, restricted ends 203 and 204 (FIGS. 2 and 4) of the transverse i and the drain bore 193, and hence between the fuel inspaced below the lower end face of the plunger, as

shown in FIG. 3, and the volume of the receiving cham: her 142 will be less than maximum. The latter condition usually occurs when an engine utilizing injectors of the character shown in FIG. 1 is operating at less than its maximum power output.

Assuming that the pressure in the fuel supply bore 0 rail has been insufiicient to maintain the ball 144engaged with the lower end 186 of the duct 184 in the control portion 117 of the plunger, as the plunger 116 begins its downward stroke fuel in the space 183 will be forced upwardly through the duct 184, outwardly through the cross bore 187 to the annular space 189, and thence through the bore 193 and circumferential groove 194 in the injector body member 102 to the drain rail in the cylinder head of the engine. The volume of the space 183 will decrease until the lower end face 145 of the plunger 116 contacts the ball 144 and the latter closes the lower end 186 of the duct 184. The latter condition is illustrated in FIG. 5.

When the lower end face 145 of the plunger 116 contacts the ball 144 on its downward stroke and the ball 144 closes the lower end 186 of the duct 184, continued downward movement of the plunger 116 will cause fuel to be displaced from the receiving chamber 142. Such displacement initially causes the check ball 140 to move upwardly against its seat 139 so that fuel will be prevented from flowing in a reverse direction through the fuel supply passage 130 and into the fuel supply rail. As soon as the check ball 140 seats, the pressure of the fuel in the receiving chamber 142, connecting bores 147, 151 and 156 of the connecting passage 146, and fuel injection chamber 143, will rapidly rise. When the pressure acting on the reaction surface 163 of the valve member 158 reaches a predetermined value sufficient to overcome the force of the coil spring 172, the valve member 158 will move upwardly in its bore 160. Consequently, fuel under high pressure in the fuel injection chamber 143 will be injected through the nozzle holes 157 and into the associated cylinder. The clearance shown in FIG. between the lower end 164 of thevalve member 158 and its seat 166 is exaggerated for clarity of illustration.

Injection continues until the control edge 206 of the reduced diameter portion 188 moves past the restricted inner ends 203 and 204 (FIGS. 2, 4 and 6) of the pressure relief bores 201 and 202. When this occurs, the pressure in the receiving chamber 142, fuel injection chamber 143, and connecting passage 146 begins to drop due to the connection established between the annular space 189 and the drain rail in the engine cylinder head through the pressure relief bores 201 and 202. However, since the inner ends 203 and 204 of the pressure relief bores 201 and 202 are restricted, the flow therethrough is small and the lower end 164 of the valve member 158 is prevented from impacting against its seat 166 at the completion of each injection cycle. In addition, the gradually decreasing pressure in the receiving chamber 142 acts on the ball 144 and hence on the plunger 1 16 to prevent overtravel of the plunger on its downward or fuel injection stroke. Hence, the possibility of damage to the ball 144 is reduced.

When the pressure in the receiving and fuel injection chambers 142 and 143 reduces to a value such as will permit the spring 172 to cause the lower end 164 of the valve member 157 to engage its seat 166, injection of fuel into the associated cylinder ceases. When the plunger 116 reaches the end of its downward or fuel injection stroke, as illustrated in FIG. 1, the injection cycle is completed.

It should be noted that the pressure relief bores 201 and 202, and their restricted inner ends 203 and 204, are arranged diametrically with respect to the plunger bore 114. Such arrangement prevents the imposition of a side load on the control portion 117 of the plunger 116 during the fuel injection phase of the injection cycle, which might cause excessive wear.

In addition, the annular grooves 150 and 155 in the lower end face of the spacer member 104 and upper end face of the nozzle member 103, respectively, prevent any unbalance of pressure forces on the engaging end faces of the members 104, 105 and 103. Consequently, any tendency of these members to cock with respect to the longitudinal axis of the injector during the fuel injection phase of the injection cycle is minimized.

THE EMBODIMENT SHOWN IN FIGS. 7-13 In FIGS. 7-13, inclusive, another fuel injector embodying the features of the present invention is illustrated. Many of the parts of the injector shown in these figures are identical with those of the injector shown in FIG. 1, and therefor have been given the same reference numerals as those of the corresponding parts in FIG. 1.

The injector shown in FIGS. 7-13, inclusive, comprises an elongated injector body 221 which, in the present instance, is of a multiple-piece construction so that replacement of the parts thereof which are subject to wear or other reason for renewal is facilitated. However, a unitary or one-piece construction could be utilized, if desired. The injector body 221 thus includes a generally cylindrical body member 222, a nozzle member 103 and a pair of generally cylindrical, upper and lower spacer members 224 and 105, respectively, located between the body member 222 and nozzle member 103. The nozzle member 103 and spacer members 224 and 105 are arranged and held in end-to-end relation by a tubular retainer 106.

The nozzle member 103 has a fuel injection chamber 143 therein provided by a cavity adjacent the lower end of the nozzle member, and the inner ends of a plurality of minute, circumferentially spaced, generally radially extending holes 157 in the lower end of the nozzle member communicate with the chamber 143 below a valve seat 166 therein. The outer ends of the holes 157 open into the cylinder with which the injector is associated. The communication between the holes 157 and chamber 143 is controlled by a valve member 158 shiftably mounted in an axial bore 160 in the nozzle member, the lower end, indicated at 164, of the valve member 158 being urged toward the seat 166 in the chamber 143 by a coil spring 172 mounted in a cavity 173 in the spacer member 105. The upper end of the cavity 173 is closed by the spacer member 104.

The nozzle member 103, spacer member 105, and retainer 106 of the injector shown in FIG. 7, the bores and passages therein, as well as the other parts in the lower portion of the injector, are identical in construction and operation with their like-numbered parts in the injector shown in FIG. 1. Consequently, no detailed description of these parts of the injector of FIG. 7 will be included.

The injector body member 222 has a central, axial bore 225 therethrough in which a plunger 226 is reciprocably mounted. The plunger 226 comprises a control portion 227 and a sleeve portion 118 secured to the upper end of the control portion 227. The sleeve portion 118 of the plunger 226, as well as the other parts at the upper end of the injector shown in FIG. 7, are likewise identical in construction and operation with the corresponding parts in the injector shown in FIG. 1, and therefore no further description of these parts will be included.

As heretofore mentioned, the injector body 221 includes variable volume chamber means for receiving a quantity of fuel from a source thereof under variable pressure, and a fuel supply passage 230 having one end connected to the variable volume chamber means and its other end adapted to be connected to said source. The other end of the fuel supply passage 230, in the present instance, includes a circumferential groove 131 in the outer surface of the body member 222, the groove 131 being adapted to register with an associated fuel supply bore or rail (not shown) in the cylinder head of the engine when the injector body 221 is seated in the cylinder head. A transverse bore 132 extends inwardly from thergroove 131 and a plug 133 (FIG. 1) havinga balancing orifice 134 therethrough is threaded into theouter end of the bore 132. A filtering screen assembly 136 may be mounted in the groove 131 around the plug 133. The balancing orifice 134 andfiltering screen assembly 1360f the injector of FIG. 7 perform the same functions as the balancing orifice 134 andfiltering screen assembly 136 of the injector of FIGLl.

The inner end of thetransverse bore 132 communicates with the upper endof a longitudinal bore 234 in the body. member. 222 and the lower end of the longitudinal bore 234 is closed, as by a plug 235. The longitu ,chamber 240, in the present instance, constitutes the portion of the plunger bore 225 between the lower end face, indicated at 2 41,0f the control portion 227 of the plunger 226 and the upper endface, indicated at 242, of a generally cylindrical piston 243 that is loosely fitted in the plunger bore 225. The clearance between the piston 243 and plunger bore 225 is exaggerated for clarity of illustration.

. In order to provide a connection between the receiving chamber 240 and the fuel injection chamber 143,

aconnecting passage, indicated generally at 245, is provided. The passage 245, in the present instance, comprises a transverse bore 246 (FIGS. 8,10 and 12) in the body member 222, the inner end of the transverse bore 246, indicated at 247,opening into the plunger bore 225 at a point somewhat below the point where the inner end 238 of the transverse fuel supply bore 238 opens into the plunger bore. The outer end of the transverse bore 246 is closed as by a plug 248. The

transverse bore 246 is intersected by a longitudinal bore 249 in the body member 222, the lower end of which registers with an annular groove 252 in the upper end face, indicated at 253, of the spacer member 224.

A longitudinal bore 254 (FIGS. 7, 9 and 11) inthe spacer member 224 connects the groove 252 with another groove 256 in the lower end face, indicated at 257, of the spacer member 224 and the groove 256 registers with the upper end of the longitudinal bore 151 in the spacer member 105. Thus, the transverse .bore 246, the portion of the longitudinal bore 249 below the transverse bore 246, groove 252, longitudinal bores 254 and 151, and the bore 156 in the nozzle member 103 comprise the connecting passage 245 which connects the receiving chamber 240 with the fuel injection chamber 143 of the injector of FIG. 7.

' As heretofore mentioned, the piston 243 of the injector shown in FIG. 7 is movable in the plunger bore 225 in response to movement of the plunger 226. Since the plunger 226 and piston 243 determine the volume of the receiving chamber .240 and since movement of the plunger 226 toward the piston 243 will reduce the volume of the receiving chamber 240 whenthe lower end face, indicated at 258, of the piston 243 is engaged with the upper end face, indicated at 253, of the spacer member 224, the plunger 226 comprises fluid displace mentmeans for reducing the volume of the receiving chamber 240. s

When the lower part of the control portion 227 of the plunger 226 closes the inner end 238 of the fuel supply bore 237 on its downward stroke, fuel is confined in the receiving chamber 240 and the pressure therein and in the fuel injection chamber 143 is increased. The lower part of the control portion 227 thus comprises preventing means for preventing fuel from. flowing from the receiving chamber through the supply passage 230 to the fuel supply rail or source.

Since the lower end face 241 of the control portion 227 of the plunger is one of the determinants of the volume of the receiving chamber 240 and since injection begins only after the 10 .ver end face 241 of the plunger 226 closes the inner end 2380f the fuel supply bore 237 and the lower end face 258 of the piston 243 has engaged the upper end face 253 of the spacer member 224, the maximum quantity of fuel that can be injected into the associated cylinder of the: engine by the injector of FIG. 7 is limited. The upperend face 253 of the spacer member 224 thus defines one end of the plunger bore 225 and such end comprises a stop for limiting movement of the piston 243 in one direction.

In order to provide for free movement of the piston 243 in the plunger bore 225 and for free movement of the valve member 159 in its bore 160, a drain passage is provided in the injector body 221 for connecting the part of the bore 225 below the lower end face 258 of the piston 243 and the valve spring cavity 173 to a drain or other low pressure zone, such as a drain rail in the engine cylinder head. Such drain passage, in the present instance, comprises an axial bore 262 through the spacer member 224 and having its upper end opening in the upper end face 253 of theQspacer member 224 and its lower end opening into the valve spring cavity 173 in the lowerportion of the injector body 221.

.A radial bore 207 in the spacer member connects the cavity 173 with an annular groove 208 in the outer periphery of the spacer member 105. The groove 208 r opens into an annular clearance 209 between the spacer members 224 and 105 and the retainer 105. The

upper end of the clearance 209 is connected to the lower end of a longitudinal bore 212 in the injector body member 222, and the upper end of the bore 212 is connected to a slanting drain bore 193 in the body member 222. The outer end of the drain bore 193 opens into a circumferential groove 194 in the outer surface of the body member 222, and the groove 194 is adapted to register with the associated drain rail in the cylinder head of the engine. Thus, the drain passage of the injector of FIG. 7 comprises the axial bore 262, spring cavity 173, transverse bore 207, groove 208, clearance 209 between the spacer members 224 and 105 and retainer 106, longitudinal bore 212, slanting bore 193, and circumferential groove 194.

of the longitudinal bore 249. The inner end, indicated at 264, of the transverse bore 263 opens into the plunger bore 225, and the outer end thereof may be closed as by a plug 266. Since the longitudinal bore 249 is connected to the receiving chamber 240 by the transverse bore 246 and since the receiving chamber 240 is connected to the fuel injection chamber 143 in the manner previously described, the transverse bore 263 is likewise connected to these chambers.

When the plunger 226 is approaching the end of its downward or fuel injection stroke, the inner end 264 of the transverse bore 263 is connected to a zone of reduced pressure, in this instance the drain bore 193. Such connection is provided by an annular reduced diameter portion 267 on the control portion 227 of the plunger, which defines an annular space 268 in the plunger bore 225 and which moves into communication with the inner end 264 of the transverse bore 263 as the plunger nears the end of its downward stroke. The inner end 192 of the slanting drain bore 193 is in continuous registry with the annular space 268 throughout the range of movement of the plunger 226.

When the inner end 264 of the transverse bore 263 is connected to the annular space 268, the pressure in the receiving chamber 240 and consequently in the fuel injection chamber 143 is relieved. As soon as the pressure in the fuel injection chamber 143 is relieved, the valve spring 172 shifts the valve member 158 downwardly until the lower end 164 thereof engages the seat 166. Seating of the lower end 164 of the valve member 158 terminates injection of fuel into the cylinder and the injection cycle of the injector of FIG. 7.

OPERATION OF THE EMBODIMENT SHOWN IN FIGS. 7-13 At the completion of an injection cycle of the injector shown in FIGS. 7-13, inclusive, and prior to the beginning of another cycle, the parts of the injector are in the positions shown in FIGS. 7 and 8. Thus, the lower end face 258 of the piston 243 will be engaged with the upper end face 253 of the spacer member 224 and the lower, full diameter part of the control portion 227 of the plunger 226 closes the inner end 238 of the fuel supply passage 230.

As the injection cycle begins, the plunger 226 moves upwardly in its bore 225. During the initial part of such movement and before the lower end face 241 of the control portion 227 of the plunger opens the inner end 238 of the fuel supply passage 230, the piston 243 will closely follow the lower end face 241 of the plunger 226 because of the suction created by upward movement of the plunger. The space in the plunger bore 225 below the piston 243 is connected to the drain rail in the cylinder head of the engine by the drain passage in the injector body 221. Such drain passage includes the axial bore 262 in the spacer member 224, spring cavity 173 and transverse bore 207 in the spacer member 105, annular clearance 209 between the spacer members 105 and 224 and the retainer 106, the longitudinal bore 212 and the slanting drain bore 193 and the circumferential groove 194 in the body member 222, which registers with the drain rail. During this portion of the injection cycle, fuel flows in a reverse direction through the aforementioned drain passage and into the space below the piston 243 as the latter moves'upwardly in the plunger bore 225.

When the lower end face 241 of the plunger 226 opens the inner end 238 of the transverse fuel supply bore 237, fuel from the fuel supply rail will flow into the receiving chamber 240 between the lower end face 241 of the plunger 226 and the upper end face 242 of the piston 243 and cause the piston to separate from the lower end face 241 of the plunger 226. Such flow continues during the remainder of the upward stroke of the plunger 226. The quantity of fuel supplied to the receiving chamber 240 depends upon the pressure of the fuel in the fuel supply rail. Thus, if the pressure of the fuel in the fuel supply rail is low, only a small amount of fuel will flow into the receiving chamber 240. Conversely, if the pressure of the fuel in the fuel supply rail is high, a comparatively large amount of fuel will flow into the receiving chamber 240.

On downward movement of the plunger 226, the lower end face 241 of the plunger closes the inner end 238 of the fuel supply bore 237 and confines fuel in the receiving chamber 240. Fuel in the plunger bore 225 below the piston 243 is displaced through the aforementioned drain passage and into the associated drain rail as the piston 243 moves downwardly.

Further downward movement of the plunger 226 causes the piston 243 to seat on the upper end face 253 of the spacer member 224 and seal the upper end of the bore 262 of the drain passage, if it has not already done so. When this occurs, the pressure in the receiving chamber 240 will rapidly rise. Such pressure rise is communicated through the connecting passage 245 to the fuel injection chamber 143 and, when the pressure reaches a predetermined value, the valve member 158 will move upwardly in its bore and the lower end 164 of the valve member 158 will lift off of its seat 166 as illustrated in FIG. 11. Consequently, fuel under pressure in the fuel injection chamber 143 will be injected through the nozzle holes 157 into the associated cylinder of the engine. The clearance shown in FIG. 11 between the lower end 164 of the valve member 158 and its seat 166 is exaggerated for clarity of illustration.

Injection of fuel through the nozzle holes 157 continues until the lower or control edge 269 of the reduced diameter portion 267 opens the inner end 264 of the transverse pressure relief bore 263 (FIG. 8) to the annular space 268. When this occurs, the pressure in the receiving chamber 240 and consequently in the fuel injection chamber 143 is immediately relieved due to the connection of these chambers with the aforementioned drain passage in the injector.

As soon as the pressure in the fuel injection chamber 143 is relieved, the spring 172 shifts the valve member 158 downwardly into engagement with the seat 166. Seating of the lower end 164 of the valve member 158 terminates injection of fuel into the cylinder and the injection cycle of the injector shown in FIG. 7.

THE EMBODIMENT SHOWN IN FIGS. 14-19 In FIGS. 14-19, inclusive, another fuel injector embodying the features of the present invention is illustrated. Many of the parts of the injector shown in these figures are identical with those of the injectors of the two previous embodiments and therefore have been given the same reference numerals as those of the corresponding parts in FIGS. 1 and 7. The injector of FIG. 14, however, is most similar in construction and operation to the injector of FIG. 7 and therefore only the differences in construction and operation of the injector of FIG. 14 from the injector of FIG. 7 will be hereinafter described in detail.

w r 17 The injector shown in FIGS. 14-19, inclusive, comprises an elongated injector body 281 which, in the present instance, is of a multiple-piece construction so that replacement of the parts thereof which are subject to wear or other reason for renewal, is facilitated. Howi ever, a unitary or one-piece construction could be utilized, if desired. The injector body 281 includes a generally cylindrical body member 222, a nozzle member 103 and a pairof generally cylindrical, upper and lower spacer members 224 and 105, respectively, located between the-body member 222 and nozzle member 103. The nozzle member 103 and spacer members 224 and 105 arearranged and held in end-to-end relation by a tubular retainer 106. a

l The nozzle member 103 has a fuel injection chamber 143 therein provided by a cavity adjacent the lower end of the nozzle member, and the inner ends of a plurality of minute, circumferentially spaced, generally radially extending holes 1 57 in the lower end of the nozzle membercommunicate with the chamber 143belo w a valve seat 166therein. The outer ends of the holes 157 open into the cylinder with which the injector is associated. The communication between the holes 157 and chamber 143 is controlled by a valve member 158 shiftably'mounted in an axial bore 160 inthe nozzle member, the lower end, indicated at 164, of the valve member 158 being urged toward the seat 166 in the chamber 143 by a coil spring 172 mounted in a cavity 173 in the spacer member 105. Theupper end of the cavity 173 is closed by the spacer member 224. The body member 222, nozzle member 103, spacer members 224 and l05,and retainer 106 of the injector shown in FIGS. 14-19, the bores and passagestherein, and the other parts in the lower portion of the injector are identicalwith their like-numbered parts in the injectors of FIGS. 1 and 7. Consequently, no detailed description of these parts of the injector of FIG. 14 will be included.

. The injector of FIG. 14 differs from the injector of FIG. 7 in that ;a portion of the fuel supply passage thereof, indicated generally at 285, is different, and the construction of thepiston, indicated generally at 290, is also different. w

The fuel supply passage 285 of the injector of FIG. 14 differs from the fuel supply passage 230 of .the injec tor 220 in that the inlet portion of the transverse fuel supply bore, indicated at 132, is unrestricted, that is, no plug, such asthe plug 133 of the injector of FIG. 7 having a balancing orifice 134 therethrough, is used. Thus, the fuel supply passage 285 of the injector of FIG. 14 presents a substantially unrestricted path to the flow of fuel into the injector from the associated fuel supply rail in the cylinder head of the engine in which the injector is mounted.

The piston 290 of the injector of FIG. 14 is similar to the piston 243 of the injector of FIG. 7 to the extent that the piston 290 is likewise generally cylindrical in form and is sized to loosely fit in the plunger bore 225. The clearance between the piston 290 and plunger bore 225 is exaggerated in FIGS. 14-18, inclusive for clarity of illustration.

The piston 290 differs from the piston 243 in that the piston 290 is hollow and has a metering spring 292 mounted therein. The spring 292 is of the coiled compression type and has its upper end engaging the inner surface of the end wall of the piston 290 and its lower end engaging the upper end face 253 member 224. 1 w

The injector of FIG. 14 is identical, in all other respects, with the injector of FIG. 7.

OPERATION OF THE EMBODIMENT SHOWN IN FIGS. 14-19 At the completion of an injection cycle of the injector shown in FIGS. 14-19, inclusive, and prior to the beginning of another cycle, the parts of the injector are in the positions shown in FIGS. 14 and 15 .Thus, the upper end face 242 of the piston 290 is held engaged with the lower end face 241 of the plunger 226 by the of the spacer force of the metering spring 292. A slight clearance may or may not be present between the lower end face 258 of the piston 290 and the upper end face 253 of the spacer member 224 at this time. In addition, the lower,

full diameter part of the control portion 227 of the plunger 226 closes the inner end 2380f the fuel supply passage 285. i i i As the injection upwardly in its bore 225. During the initial part of such movement and before the lower end face 241 of the control portion 227 of the plunger opens theinnerend 238 of the fuel supply bore 237, the piston 290 will be moved upwardly in the bore 225 by the force of the inetering spring 292. At this time, the upper end face242 of the piston 290 will be maintained in engagement with the lower end 241 of the plunger 226. Since upward movement of the plunger 22S and piston 290 create suction in 'the space or clearance below the lower end face 258 of the piston 290, fuel from the associated drain rail in the cylinder head of the engine will flow in a reverse direction through the drain passage into the space. The various bores and cavities in the injector body 281 which constitute the drain passage of the injector of FIG. 14 are the same as those of the injector of FIG. 7.

When the lower end face 241 of the plunger 226 opens the inner end 238 of the transverse fuel supply bore 237, fuel from the fuel supply rail will flow into the receiving chamber 240 and act upon the piston 290 and to oppose the force of the metering spring 292. The pressure in the receiving chamber 240 will be substantially the same as the pressure in the fuel supply rail due to the unrestricted character of the fuel supply passage 285. Thus, the piston 290 and the plunger 226 willbe caused to separate by an amount proportional to the pressure of the fuel in the fuel supply passage 285. Such flow continues during the remainder of the upward stroke of the plunger 226. i

The quantity of fuel supplied to the receiving chamber 240 depends substantially only upon the pressure of the fuel inthe fuel supply rail. Thus, if the pressure of the fuel in the fuel supply rail is low, only a small amount of fuel will flow into the receiving chamber sage in the injector body 281 and into the associated drain rail, in the same manner as in the injector of FIG. 7.

cycle begins, the plunger 226 moves a Further downward movement of the plunger 226 causes the lower end face 258 of the piston 290 to seat onthe upper end face 253 of the spacer member 224 and seal the upper end of the bore 262 of the drain passage, if it has not already done so. When this occurs, the pressure in the receiving chamber 240 rapidly rises. Such pressure rise is communicated through the passage means 245 to the fuel injection chamber 143. When the pressure in the fuel injection chamber 143 reaches a predetermined value, the valve member 158 will move upwardly in its bore 159 and the lower end 164 of the valve member will lift off of its seat 166 as illustrated in FIG. 17. Consequently, fuel under pressure in the fuel injection chamber 143 will be injected through the nozzle holes 157 into the associated cylinder of the engine. The clearance shown in FIG. 17 between the lower end 164 of the valve member 157 and its seat 166 is exaggerated for clarity of illustration.

Injection of fuel through the nozzle holes 157 continues until the lower or control edge 269 of the reduced diameter portion 267 opens the inner end 264 of the transverse pressure relief bore 263 (FIG. 18) to the annular space 268. When this occurs, the pressure in the receiving chamber 240 and the pressure in the fuel injection chamber 143 is immediately relieved due to the connection of these chambers with the aforementioned drain passage in the injector. As soon as the pressure in the fuel injection chamber 143 is relieved, the spring 172 shifts the 'valve member 158 downwardly into engagement with the seat 166. Seating of the lower end 164 of the valve member 158 terminates injection of fuel into the cylinder and the injection cycle of the injector.

As in the injector illustrated in FIG. 7, since the lower end face 241 of the plunger 226 of the injector of FIG. 14 is one of the determinants of the volume of the receiving chamber 240 and since injection of fuel begins only after the lower end face 241 of the plunger closes the inner end 238 of the fuel supply bore 237 and the lower end face 258 of the piston 243 has engaged the upper end face 223 of spacer member 224, the maximum quantity of fuel that can be injected by the injector of FIG. 14 is limited.

Thus, the injector illustrated in FIG. 14 may be characterized as a pressure controlled injector in that, due to the unrestricted character of the fuel supply passage 285 thereof, the quantity of fuel supplied to the receiving chamber 240 and consequently the quantity of fuel injected into the associated cylinder of the engine is determined substantially only by the pressure of the fuel in the associated fuel supply rail.

TI-IE EMBODIMENT SHOWN IN FIGS 20-25 In FIGS. 20-25, inclusive, another fuel injector embodying the features of the present invention is illustrated. Many of the parts of the injector shown in these figures are identical with those of the injector shown in FIG. 1 and therefore have been given the same reference numerals as those of the corresponding parts in FIG. 1. Therefore only the differences in construction and operation of the injector of FIG. 20 from the injector of FIG. 1 will be hereinafter described in detail.

The injector shown in FIGS. 20-25, inclusive, comprises an elongated injector body 301 which, in the present instance, is of a multiple-piece construction so that replacement of the parts thereof which are subject to wear or other reason for renewal, is facilitated. However, a unitary or one-piece construction could be utilized, if desired. The injector body 301 includes a generally cylindrical body member 302, a nozzle member 103 and a pair of generally cylindrical, upper and lower spacer members 304 and 105, respectively, located between the body member 302 and nozzle member 103.

The nozzle member 103 and spacer members 304 and 105 are arranged and held in end-to-end relation by a tubular retainer 106.

The nozzle member 103 has a fuel injection chamber 143 therein provided by a cavity adjacent the lower end of the nozzle member, and the inner ends of a plurality of minute, circumferentially spaced, generally radially extending holes 157 in the lower end of the nozzle member communicate with the chamber 143 below a valve seat 166 therein. The outer ends of the holes 157 open into the cylinder with which the injector is associated. The communication between the holes 157 and chamber 143 is controlled by a valve member 158 shiftably mounted in an axial bore 160 in the nozzle member, the lower end, indicated at 164, of the valve member158 being urged toward the seat 166 in the chamber 143 by a coil spring 172 mounted in a cavity 173 in the spacer member 105. The upper end of the cavity 173 is closed by the spacer member 304.

The spacer member 105, nozzle member 103, retainer 106, and the bores and passages therein, as well as the other parts in the lower portion of the injector body 301 are identical with their like-numbered parts in the injector of FIG. 1. Consequently, no detailed description of these parts of the injector of FIG. 20 will be included.

The injector body member 302 has a central, axial bore 305 therethrough in which a plunger 306 is reciprocably mounted. The plunger 306 comprises a control portion 307 and a sleeve portion 118 secured to the upper end of the control portion 307. The sleeve portion 118 of the plunger 306, as well as the other parts at the upper end of the injector shown in FIG. 20, are identical in construction and operation with the corresponding parts of the injector shown in FIG. 1 and therefore no further description of these parts will be included.

The injector of FIG. 20 differs from the injector of FIG. 1 primarily in the construction of the fuel supply passage thereof, and also in the construction of the upper spacer member 304. Thus, the fuel supply passage of the injector of FIG. 20, which is indicated generally at 310, has one end connected to a variable volume chamber means in the injector body 301 and its other end adapted to be connected to a source of fuel under variable pressure. The other end of the fuel supply passage 310 is provided by a circumferential groove 131 in the outer surface of the injector body member 302, the groove 131 being adapted to register with an associated fuel supply bore or rail in the cylinder head of the engine.

The fuel supply passage 310 also includes a transverse bore 132 which extends inwardly from the groove 131, and a plug 133 having a balancing orifice 134 therethrough is threaded into the outer end of the transverse bore 132. A filtering screen assembly 136 may be mounted in the groove 131 around the plug 133. The balancing orifice 134 and filtering screen assembly 136 of the injector of FIG. 20 perform the same functions as the balancing orifice 134 and filtering screen assembly 136 of the injector of FIG. 1, that is, 

1. An injector for injecting fuel into a cylinder of an internal combustion engine, comprising an injector body having a fuel injection chamber provided with an opening adapted to communicate with said cylinder, a valve member in said body and normally closing said opening, said valve member being movable to a position permitting fuel flow from said fuel injection chamber through said opening when the pressure of the fuel in said fuel injection chamber reaches a predetermined value, fluid displacement means movably mounted in said injector body and defining a receiving chamber therein, said injector body also having a connecting passage connecting said receiving chamber with said fuel injection chamber and a supply passage adapted to connect said receiving chamber with a source of fuel under variable pressure for supplying varying quantities of fuel to said receiving chamber, the volume of said receiving chamber being determined by the extent of movement of said fluid displacement means and limited to a predetermined maximum when said fluid displacement means is moved fully in one direction, and said fluid displacement means being movable in the opposite direction to reduce the volume of said receiving chamber and increase the pressure therein and thereby move said valve member to an open position whereby a quantity of fuel from said fuel injection chamber is injected through said opening into said cylinder, said injector body having a bore therein, said fluid displacement means comprising a piston and a reciprocable plunger in said bore, and said plunger being operable to move said piston in said opposite direction, said receiving chamber being located between said piston and one end of said bore, said plunger having a reduced diameter portion defining a space in said bore and a duct therein having one end communicating with said plunger bore between said plunger and said piston, said one end of said duct being positioned to be closed by said piston during movement of said plunger in said opposite direction, the other end of said duct communicating with said space, and said injector body has a drain bore therein having one end opening into said plunger bore in constant registry with said space and the other end adapted to be connected to a drain, said duct, said space, and said drain bore comprising a drain passage in said injector body pErmitting fuel to be freely drawn into or expelled from between said plunger and said piston when said one end of said duct is open.
 2. An injector for injecting fuel into a cylinder of an internal combustion engine, comprising an injector body having a chamber formed therein and a passage for connecting said chamber with said cylinder, a valve member movably mounted in said passage and normally being in a first position where it closes said opening, said valve member being movable by fuel pressure thereon to a second position where it opens said opening to enable injection of fuel, a plunger and a piston movably mounted in said chamber, said plunger being adapted to be driven in an injection stroke and in a return stroke, said body further including first passage means therein adapted to be connected with a source of fuel under variable pressure and second passage means therein adapted to be connected with a low pressure zone, said first passage means communicating with said chamber on one side of said piston and said second passage means communicating with said chamber on the other side of said piston, said second passage means being open during at least a portion of said return stroke and being closed by said piston during at least a portion of said injection stroke, said plunger exerting pressure on fuel in said chamber when said second passage means is closed during said portion of said injection stroke and thus moving said valve member to said second position, and spill passage means connected to said chamber and located to be opend by movement of said plunger to terminate injection, said plunger and said piston being axially aligned in said chamber, and said second passage means including a hole formed in said plunger.
 3. An injector for injecting fuel into a cylinder of an internal combustion engine, comprising an injector body having a chamber formed therein and a passage for connecting said chamber with said cylinder, a valve member movably mounted in said passage and normally being in a first position where it closes said opening, said valve member being movable by fuel pressure thereon to a second position where it opens said opening to enable injection of fuel, a plunger and a piston movably mounted in said chamber, said plunger being adapted to be driven in an injection stroke and in a return stroke, said body further including first passage means therein adapted to be connected with a source of fuel under variable pressure and second passage means therein adapted to be connected with a low pressure zone, said first passage means communicating with said chamber on one side of said piston and said second passage means communicating with said chamber on the other side of said piston, said second passage means being open during at least a portion of said return stroke and being closed by said piston during at least a portion of said injection stroke, said plunger exerting pressure on fuel in said chamber when said second passage means is closed during said portion of said injection stroke and thus moving said valve member to said second position, and spill passage means connected to said chamber and located to be opened by movement of said plunger to terminate injection, the portion of said chamber containing said valve member being connected to the remainder of said chamber by a connecting passage, said connecting passage opening into said one side.
 4. A fuel injector comprising an injector body having a fuel receiving chamber formed therein, a plunger reciprocably mounted in said body and cyclically movable in an injection stroke and in a return stroke, said body having a fuel supply passage therein adapted to be connected to receive fuel from a variable pressure fuel supply and a spill passage therein adapted to be connected to a low pressure zone, said plunger when moving in one portion of its cycle of movement opening said supply passage for flow of fuel from said supply into said chamber and when in another portion of said cycle opening said spilL passage for flow of fuel out of said chamber to said zone, said body further having spray holes formed therein and an injection passage connecting said chamber with said spray holes, a fuel pressure actuated valve in said injection passage, said valve being opened by fuel pressure in said chamber and in said injection passage during the time that said supply passage and said spill passage are closed by said plunger during said injection stroke, said pressure in said chamber being caused by movement of said plunger in said injection stroke and the amount of fuel entering said injection chamber being a function of the pressure of the fuel received from said fuel supply down to substantially zero fuel supply pressure, and further including a member movably mounted in said body and having one side thereof forming a wall of said receiving chamber, said body further having passage means therein adapted to connect a low pressure zone to the side of said member which is opposite said one side, whereby said member is movable to vary the size of said chamber as fuel flows into said chamber from said supply and said passage to said zone prevents suction from occurring while said plunger is moving in said return stroke, the flow of fuel from said supply passage and into said chamber being controlled only by the movement of said plunger, whereby the quantity of fuel flowing into said chamber is determined by the pressure of the fuel from said supply and may be varied down to substantially zero quantity.
 5. A fuel injector comprising an injector body having a fuel receiving chamber formed therein, a plunger reciprocably mounted in said body and cyclically movable in an injection stroke and a return stroke, said body having a fuel supply passage therein adapted to be connected to receive fuel from a variable pressure fuel supply and a spill passage therein adapted to be connected to a low pressure zone, said plunger when moving in one portion of its cycle of movement opening said supply passage for flow of fuel from said supply into said chamber and when in another portion of said cycle opening said spill passage for flow of fuel out of said chamber to said zone, said body further having spray holes formed therein and an injection passage connecting said chamber with said spray holes, a fuel pressure actuated valve in said injection passage, said valve being opened by fuel pressure in said chamber and in said injection passage during the time that said supply passage and said spill passage are closed by said plunger during said injection stroke, said pressure in said chamber being caused by movement of said plunger in said injection stroke, and a member movably mounted in said body and having one side thereof forming a wall of said receiving chamber, said body further having passage means therein adapted to connect a low pressure zone to the side of said member which is opposite said one side, whereby said member is movable to vary the size of said chamber as fuel flows into said chamber from said supply and said passage to said sump prevents suction from occurring while said plunger is moving in said return stroke, the flow of fuel from said supply passage and into said chamber being controlled only by the movement of said plunger, whereby the quantity of fuel flowing into said chamber is determined by the pressure of the fuel from said supply and may be varied down to substantially zero quantity.
 6. A fuel injector as in claim 5, and further including fuel flow restricing orifice means mounted in said supply passage.
 7. An engine injector for operation in a fuel system including means for supplying fuel to said injector and for controlling the fuel pressure in order to control the quantity of fuel injected by the injector in each cycle of operation, said injector comprising an injector body having chamber means formed in said body and connected to receive fuel through a normally open passageway from said pressure controlling means, the quantity of the fuel flowing into said chambeR means being a function of the pressure of the fuel, spray holes formed in said body for connecting said chamber means with a combustion chamber of the engine, a normally closed valve positioned to control the flow of fuel out of said chamber means through said holes, said valve being openable to enable fuel flow only when the fuel pressure in said chamber means is above a predetermined value, fluid displacement means mounted in said body and reciprocably movable in an injection stroke and in a retraction stroke, said displacement means during said injection stroke trapping fuel in said chamber means and exerting pressure on said trapped fuel to above said predetermined value and thereby opening said valve, spill port means connected to said chamber means and located to be opened by movement of said displacement means at the end of said injection stroke, said opening of said spill port means venting a portion of said trapped fuel from said chamber means and resulting in prompt closure of said valve, and said body further having passage means therein adapted to be connected to a low pressure fuel zone, said passage means being open during at least a portion of said retraction stroke to permit low pressure fuel to flow from said zone into said chamber means during said retraction stroke.
 8. An injector as in claim 7, and further including means in said normally open passageway forming a balance orifice.
 9. An injector as in claim 7, wherein said spill port means is connected to vent trapped fuel to said low pressure fuel zone.
 10. An injector as in claim 7, wherein said spill port means is connected to vent trapped fuel to said normally open passageway.
 11. An injector as in claim 7, wherein said normally closed valve means includes a valve seat, a valve member, and a spring urging said valve member toward said valve seat, one end of said valve member being exposed to said trapped fuel pressure in said chamber means, and the other end of said valve member being exposed to said low pressure fuel zone.
 12. An injector as in claim 11, wherein said plunger engages said spring and varies the force exerted by said spring with movement of said plunger.
 13. An injector as in claim 7, wherein said displacement means comprises a plunger and a piston, said piston being movable in said chamber means.
 14. An injector as in claim 13, wherein said plunger and said piston are movable along a single axis.
 15. An injector as in claim 13, wherein said plunger is movable along a first axis and said piston is movable along a second axis, said first and second axes being laterally displaced in said injector body.
 16. An injector as in claim 13, wherein the pressure of said trapped fuel in said chamber means urges said piston in a first direction, and further including a metering spring connected to said piston and urging said piston in the opposite direction against said pressure of said trapped fuel.
 17. An injector as in claim 16, wherein said metering spring is a linear spring.
 18. An injector as in claim 13, wherein said piston is movable to close said passage means during said injection stroke, said piston being moved by fuel pressure caused by movement of said plunger.
 19. An injector as in claim 18, wherein a portion of said passage means is formed in said plunger, and said plunger and said piston engage to close said portion of said passage means during said injection stroke.
 20. An injector as in claim 13, wherein said normally open passageway, said spill port and said spray holes are all connected to said chamber means on one side of said piston, and said passage means is connected to said chamber means on the other side of said piston.
 21. An injector as in claim 20, wherein said one side of said piston comprises its side which is adjacent said plunger.
 22. An injector as in claim 20, wherein said one side of said piston comprises its side which is away from said plunger. 